Core tip: For the threads of triangular screws used in fasteners, the three major elements of tooth form, diameter and pitch are all load standard threads called standard threads, tolerance zones and thread marks of standard threads

For the threads of triangular screws used in fasteners, the three major elements of tooth type, diameter and pitch are all load standard threads called standard threads. The tolerance zone and thread marks of standard threads have been standardized, and the number of threads And the direction of rotation, if not specifically noted, it is single-line right-handed. If you want the internal and external threads to be correctly screwed together to form a thread pair, the profile, diameter, direction of rotation, number of lines and pitch of the internal and external threads must be consistent.

The main elements of the thread of the triangle screw are as follows:

1. Tooth type. On the section passing through the thread axis, the profile shape of the thread is called the tooth type. The angle between two adjacent flanks is called the profile angle. Commonly used common thread has a triangular profile with a profile angle of 60°.
2. Diameter, the diameter of the thread has a large diameter, a middle diameter, and a small diameter. The nominal diameter is used when expressing the thread, and the nominal diameter is the diameter that represents the size of the thread. The nominal diameter of an ordinary thread is the major diameter.
3. Rotation direction, viewed along the axis, the thread that rotates clockwise becomes a right-hand thread, and the thread that rotates counterclockwise is called a left-hand thread.
4. The number of threads, the number of spiral threads forming a thread is called the number of threads. There are single-thread and multi-thread threads. The multi-thread threads are evenly distributed in the section perpendicular to the axis.
5. Pitch, the axial distance between two adjacent teeth on the median diameter line corresponding to two points is called the pitch. On the same spiral line, the axial distance between two adjacent teeth corresponding to two points on the median diameter line is called the lead.